External contact to copper-oxide rectifiers



EXTERNAL CONTACT TO corPnn-oxing QRECTIIFIERS Filed Ma 6,. 193a Graphite layer 4 Tin-33? Lead 7 v /////////////Cu WITNESSES. INVENTOR lalzyfbl'd TBourland;

I BY I Ano'l m Patented July 4,1939 i 2,165,029 I UNITED STATES PATENT OFFICE EXTERNAL CONTACT TO COPPER-OXIDE RECTIFIERS Langford T. Bourland, Forest Hills, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 6, 1938, Serial No. 206,316

3 Claims. (01.175-366) My invention relates to a conductive layer conthat which is substantially a eutectic alloy of the tact and especially to a contact layer applied to metals. This eutectic alloy gives a minimum the copper-oxide contact rectifier. melting point making feasible the use of an in- An object of the invention is to provide a conexpensive metal spray gun in forming a thin 5 I tact layer which possesses sustained high conlayer overthe copper-oxide surface or the copperductivity and one whose application should not oxide surface coated with graphite material. injure the' delicate material of the device. This eutectic alloy does not-require the more Other objects and advantages of the invention highly skilled technic in applying the layer that will be apparent from the following description is necessary with higher melting alloys. I

and drawing, the single figure of which is a cross- The lead-tin alloy is stable against changes sectional'view which illustrates the preferred due to contact with the atmosphere, and the embodiment of the invention. materials are not costly, and the combination The contacts applied to the copper-oxide rectihaving a low melting point permits the use of an u fiers heretofore have caused considerable trouble inexpensive metal Spray either from their change of high conductivity It is apparent that the invention may have apby reaction in time with the atmosphere, or beplication to other electrical devices, especially cause of the method ofapplying the contact to where a layer of copper-oxide or other delicate the copper oxide injures the oxide layer either compound isused, and accordingly I desire only initially or with time. This is especially true such limitations to be imposed upon the followwith the type of contact which puts a high presing claims as are necessitated by the prior art. sure directly upon the copper-oxide layer. Iclaim as my invention:

My invention ccncerns applying an alloy of tin 1. An electrical device including a layer of copnd lead to the surface of the contact rectifier per oxide and a contactthereto including a layer as a conductive layer thereto. This layer may of an alloy 01' from 50% t0 tin and t0 be placed directly upon the cuprous oxide surleadface, or a cuprous oxide surface that has been 2. A contact rectifier having a rectifyin layer treated with graphite, preferably in the form of of a material and a comp 01 said material so graphite in solution, such as that sold under the and a conductive layer therefor comprising a trade name of Aquadag". The alloy of the coneutectic alloy of tin and lead. ductive layer may be from 5% to 95% tin and. 3. A contact rectifier comprising copp copper 95%to5% lead. Mypreferred range is from 5 0% oxide and a conductive layer of approximately to 85% tin and 15% to lead. Especially I 63% tin and 37% lead. prefer to use approximately 63% tin and 37% f lead. The preferred percentage of materials is LANGFORD 'I'. BOUBLAND. 

